While inspecting an engine valvetrain, a mechanic measures the outside diameter of a pushr… — Armed Services Vocational Aptitude Battery (ASVAB)

While inspecting an engine valvetrain, a mechanic measures the outside diameter of a pushrod using a micrometer graduated in thousandths of an inch. The sleeve displays the major digit $3$ and reveals $2$ full minor tick marks past the digit. The thimble bevel aligns precisely on the graduation mark $14$ . What is the pushrod diameter measurement?

A
$0.314\text{ inch}$
B
$0.339\text{ inch}$
$0.364\text{ inch}$ Answer
D
$0.389\text{ inch}$

Answer

The measured pushrod diameter is

0.364\text{ inch}

The total reading is obtained by combining the major sleeve increment of

0.300\text{ inch}

, the two visible minor subdivision marks (

2 \times 0.025\text{ in.} = 0.050\text{ inch}

), and the thimble graduation of

0.014\text{ inch}

, resulting in

0.300 + 0.050 + 0.014 = 0.364\text{ inch}

Step-by-Step Solution

Read the largest visible major number on the sleeve and multiply by

0.100\text{ inch}

3 \times 0.100\text{ in.} = 0.300\text{ inch}

Each numbered graduation line along the sleeve represents one-tenth (

0.100

) of an inch.

Count the visible minor subdivision marks between the major digit and the thimble edge, multiplying by

0.025\text{ inch}

2 \times 0.025\text{ in.} = 0.050\text{ inch}

Each subdivision line represents one complete turn of the thimble, equal to

0.025\text{ inch}

Read the thimble graduation mark that aligns with the sleeve index line and multiply by

0.001\text{ inch}

14 \times 0.001\text{ in.} = 0.014\text{ inch}

The thimble is divided into 25 equal increments of one-thousandth (

0.001

) of an inch each.

Calculate the total measurement by adding the three individual scale readings together.

0.300 + 0.050 + 0.014 = 0.364\text{ inch}

The final reading is the sum of the sleeve major reading, sleeve minor increments, and the aligned thimble value.

Key Concept

Reading a standard inch outside micrometer by summing the major sleeve divisions (

0.100\text{ in.}

), minor sleeve subdivisions (

0.025\text{ in.}

), and thimble graduations (

0.001\text{ in.}

Estimated Time:45s

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